Dr. Laurience (Karloff), a once-respectable scientist, begins to research the origins of the mind and soul in an isolated manor house, aided only by the promising surgeon Clare Wyatt (Lee) and a wheelchair-using confederate named Clayton (Donald Calthrop). The scientific community rejects his theories and Laurience risks losing everything for which he has worked so obsessively. To save his research, Laurience (pronounced "Lorenz") begins to use his discoveries in brain transference for his own nefarious purposes, replacing the mind of philanthropist Lord Haslewood (Frank Cellier (actor)) with the personality of the crippled, caustic Clayton. With Lord Haslewood's wealth and prestige at his command, Laurience becomes an almost unstoppable mad scientist.